The present invention relates generally to high temperature melting ternary alloys, and more particularly to high temperature melting molybdenum-chromium-silicon alloys having a wide range of desirable microstructures, excellent microstructural and morphological stability, and superior oxidation resistance at temperatures of about 1000.degree. C. to 1500.degree. C.
Conventional (primarily nickel-based) superalloys presently used in high temperature engine applications may be inadequate to meet temperature requirements of advanced aerospace systems. New refractory material systems with improved high temperature capability are required with low-temperature damage tolerance and high-temperature strength and creep resistance in addition to superior environmental stability. Selected ordered intermetallic compounds under consideration for high temperature application have high melting temperatures and high stiffness, low densities, and good strength retention at elevated temperatures, but, in monolithic form, have inadequate damage tolerance and extremely low fracture toughness at low temperatures.
The invention solves or substantially reduces in critical importance problems associated with conventional high temperature alloys for engine applications by providing high melting molybdenum-chromium-silicon (Mo--Cr--Si) alloys and method for making them, the novel alloys of the invention comprising a ductile, refractory phase uniformly distributed within a high temperature melting intermetallic matrix, wherein the two phases are in stable thermochemical equilibrium at or above 1500.degree. C., and wherein plasticity of the ductile phase substantially enhances the overall fracture resistance of the alloy and the matrix has good high-temperature strength and creep resistance.
It is therefore a principal object of the invention to provide improved high temperature melting molybdenum-chromium-silicon alloys.
It is a further object of the invention to provide improved molybdenum-chromium-silicon alloys having a wide range of deskable microstructures.
It is another object of the invention to provide improved molybdenum-chromium-silicon alloys having excellent microstructural and morphological properties.
It is another object of the invention to provide molybdenum-chromium-silicon alloys having superior oxidation resistance at temperatures from 1000.degree. C. to 1500.degree. C.
It is yet another object of the invention to provide molybdenum-chromium-silicon alloys having good low temperature toughness and good high temperature strength and creep resistance.
It is yet another object of the invention to provide improved high temperature melting molybdenum-chromium-silicon alloys for advanced aerospace propulsion systems and air vehicles.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.